Antenna pattern matching and mounting

ABSTRACT

A technique for improving wireless communication characteristics involving matching transmitter antenna patterns to receiver antenna patterns. In a specific implementation, the transmitter antenna pattern adapts to changing parameters, such as when a smartphone is initially held in a first orientation and is later held in a second orientation. Because the transmitter antenna patterns match the receiver antenna patterns, signal quality between stations improves. In some implementations, antennas are organized and mounted to maximize spatial diversity to cause peak gains in different directions.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/078,434, filed Nov. 12, 2013, entitled “Antenna PatternMatching and Mounting,” which claims priority to and the benefit of U.S.Provisional Patent Application Ser. No. 61/762,238, filed Feb. 7, 2013,entitled “Antenna Pattern Matching,” and U.S. Provisional PatentApplication Ser. No. 61/725,435, filed Nov. 12, 2012, entitled “SmartAntenna Wireless Network Device,” all of which are incorporated hereinby reference. This application also claims priority to and the benefitof U.S. Provisional Patent Application Ser. No. 61/762,238, filed Feb.7, 2013, entitled “Antenna Pattern Matching.”

BACKGROUND

An area of ongoing research and development is in improving wirelesscommunication signal quality, speed, efficiency, or othercharacteristics. Wireless networks are frequently governed by 802.11standards. While not all networks need to use all of the standardsassociated with 802.11, a discussion of the standards by name, such as802.11n provides, at least partly because the standards are well-knownand documented, a useful context in which to describe issues as theyrelate to wireless systems.

A specific area of wireless communication research and development ismultiple-input multiple-output (MIMO). With MIMO, a transmitter may havemultiple antennas for transmitting signals and a receiver may havemultiple antennas for receiving the signals. For example, in a 3×3(three transmitters and three receivers) MIMO system, stations can usethree antennas to transmit and three antennas to receive. Most wirelesslocal area network (WLAN) wireless access points (WAP) are capable of2×2 or 3×3, though there is a small percentage of low-cost WAP that onlysupport 1×1, 4×4 WLAN WAP are expected to hit the market soon, andhigher-value MIMO is possible. For example, laptops often have 2×2 or3×3 MIMO WLAN stations and smart phones often have 1×1 MIMO WLANstations, with the lower values used primarily to conserve batterypower. (Wireless data transmission is one of the biggest power drains onsmart phone batteries.)

The foregoing examples of the related art are intended to beillustrative and not exclusive. For example, wireless stations may usedifferent protocols other than 802.11, potentially including protocolsthat have not yet been developed. However, problems associated withimproving wireless communication characteristics. Other limitations ofthe relevant art will become apparent to those of skill in the art upona reading of the specification and a study of the drawings.

SUMMARY

The following embodiments and aspects thereof are described andillustrated in conjunction with systems, tools, and methods that aremeant to be exemplary and illustrative, not necessarily limiting inscope. In various embodiments, one or more of the above-describedproblems have been addressed, while other embodiments are directed toother improvements.

A technique for effective antenna pattern searching involves matchingtransmitter antenna patterns to receiver antenna patterns. There couldbe numerous antenna patterns within a multiple-input multiple-output(MIMO) antenna system in a wireless access points (WAP) when a transmitantenna has many different patterns to choose from. In a specificimplementation, antenna patterns are grouped and categorized by stationtypes in order to reduce the number of patterns to search for eachstation type. When a station associates with a WAP, the WAP can profilethe station in a first of multiple categories, such as 1×1, 2×2, 3×3, or4×4; or in accordance with some other antenna or spatial streamconfiguration, characteristic, or parameter. The WAP can group discreteantenna patterns into station antenna pattern profiles that are eachassociated with a station type. The WAP can then determine that astation is of a specific station type having an associated stationantenna pattern profile. The WAP can select an antenna pattern groupcorresponding to the station type. The WAP can select the antennapattern group by using the station antenna pattern profile that isassociated with the station type. The WAP can then search the antennapattern group to determine an optimal antenna pattern. The WAP cansearch a subplurality of the antenna patterns in the antenna patterngroup to determine an optimal antenna pattern. In this way, the numberof patterns searched before reaching an apparently optimal antennapattern is reduced and/or the efficiency of a search algorithm can beimproved. Because a transmitter antenna pattern matches a receiverantenna pattern, signal quality between stations improves.

In a specific implementation, the transmitter antenna pattern adapts tochanging parameters, such as when a smartphone is initially held in afirst orientation and is later held in a second orientation.

Techniques described herein also include techniques for mountingantennas along a circle or a projection of a circle and according totheir polarization.

These and other advantages will become apparent to those skilled in therelevant art upon a reading of the following descriptions and a study ofthe several examples of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a diagram of an example of system in which a fast antennapattern group matching station efficiently matches an antennaconfiguration to an antenna pattern associated with another station.

FIG. 2 depicts a diagram of an example of a system for antenna patterngroup matching.

FIG. 3 depicts a diagram an example of a MIMO channel between a dynamicantenna device and a station.

FIG. 4 depicts a flowchart of an example of a method for matching a WAPantenna pattern to a station antenna pattern with an unknown parameter.

FIG. 5 depicts a diagram of a grouping of antenna patterns for a MIMO(and potentially and applicable degenerate form of MIMO) antenna arraycomprising four antennas.

FIG. 6 depicts a flowchart of an example of a method for antenna patternmatching at a WAP.

FIG. 7 depicts a diagram of an example of a wireless network system witha smart antenna wireless network device.

FIG. 8 depicts a diagram of an example of an antenna board withspatially diverse antennas.

FIG. 9 depicts a diagram of an example of a wireless network device withantennas mounted around a printed circuit board (PCB) edge in a circularmanner.

FIGS. 10A and 10B depict top and side view diagrams and of an example ofa wireless network device with an antenna board.

DETAILED DESCRIPTION

FIG. 1 depicts a diagram 100 of an example of system in which an antennapattern group matching station efficiently matches an antennaconfiguration to an antenna pattern associated with another station. Inthe example of FIG. 1, the diagram 100 includes a wireless network 102,a fast antenna pattern group matching station 104, stations 106-1 to106-N (collectively, stations 106), and a network 108.

In the example of FIG. 1, the wireless network 102 is intended torepresent a wide variety of applicable wireless network technologies. Asused herein, a wireless network refers to any type of wireless network,including but not limited to a structured network or an ad hoc network.Data on a wireless network is often encrypted. However, data may also besent in the clear, if desired. With encrypted data, a rogue device willhave a difficult time learning any information (such as passwords, etc.)from stations before countermeasures are taken to deal with the rogue,assuming countermeasures are necessary.

The wireless network 102 may or may not be IEEE 802.11-compatible. Inthis paper, 802.11 standards terminology is used by way of relativelywell-understood example to discuss implementations that include wirelesstechniques. For example, a station, as used in this paper, may bereferred to as a device with a media access control (MAC) address and aphysical layer (PHY) interface to a wireless medium that complies withthe IEEE 802.11 standard. Thus, for example, stations and a wirelessaccess point (WAP) with which the stations associate can be referred toas stations, if applicable. IEEE 802.11a-1999, IEEE 802.11b-1999, IEEE802.11g-2003, IEEE 802.11-2007, and IEEE 802.11n TGn Draft 8.0 (2009)are incorporated by reference. As used in this paper, a system that is802.11 standards-compatible or 802.11 standards-compliant complies withat least some of one or more of the incorporated documents' requirementsand/or recommendations, or requirements and/or recommendations fromearlier drafts of the documents, and includes Wi-Fi systems. Wi-Fi is anon-technical description that is generally correlated with the IEEE802.11 standards, as well as Wi-Fi Protected Access (WPA) and WPA2security standards, and the Extensible Authentication Protocol (EAP)standard. In alternative embodiments, a station may comply with adifferent standard than Wi-Fi or IEEE 802.11, may be referred to assomething other than a “station,” and may have different interfaces to awireless or other medium.

IEEE 802.3 is a working group and a collection of IEEE standardsproduced by the working group defining the physical layer and data linklayer's MAC of wired Ethernet. This is generally a local area networktechnology with some wide area network applications. Physicalconnections are typically made between nodes and/or infrastructuredevices (hubs, switches, routers) by various types of copper or fibercable. IEEE 802.3 is a technology that supports the IEEE 802.1 networkarchitecture. As is well-known in the relevant art, IEEE 802.11 is aworking group and collection of standards for implementing wirelesslocal area network (WLAN) computer communication in the 2.4, 3.6 and 5GHz frequency bands. The base version of the standard IEEE 802.11-2007has had subsequent amendments. These standards provide the basis forwireless network products using the Wi-Fi brand. IEEE 802.1 and 802.3are incorporated by reference.

In a specific implementation, the wireless network 102 includes a WLAN.Administrative control of a WLAN may or may not include ownership ofhardware for an implementation that includes offering computingresources as a service. In a specific implementation, the wirelessnetwork 102 includes a cloud network.

In the example of FIG. 1, the fast antenna pattern group matchingstation 104 is coupled to the wireless network 102. In a specificimplementation, the fast antenna pattern group matching station 104 isimplemented as a WAP of an infrastructure network. In another specificimplementation, the fast antenna pattern group matching station 104 isimplemented as a node of an ad-hoc network. Some functionality,described later, attributable to the fast antenna pattern group matchingstation 104 can be carried out at an upstream computer system,distributed to other stations, or carried out by an on-device computersystem.

A computer system, as used in this paper, is intended to be construedbroadly. In general, a computer system will include a processor, memory,non-volatile storage, and an interface. A typical computer system willusually include at least a processor, memory, and a device (e.g., a bus)coupling the memory to the processor. The processor can be, for example,a general-purpose central processing unit (CPU), such as amicroprocessor, or a special-purpose processor, such as amicrocontroller.

The memory can include, by way of example but not limitation, randomaccess memory (RAM), such as dynamic RAM (DRAM) and static RAM (SRAM).The memory can be local, remote, or distributed. As used in this paper,the term “computer-readable storage medium” is intended to include onlyphysical media, such as memory. As used in this paper, acomputer-readable medium is intended to include all mediums that arestatutory (e.g., in the United States, under 35 U.S.C. 101), and tospecifically exclude all mediums that are non-statutory in nature to theextent that the exclusion is necessary for a claim that includes thecomputer-readable medium to be valid. Known statutory computer-readablemediums include hardware (e.g., registers, random access memory (RAM),non-volatile (NV) storage, to name a few), but may or may not be limitedto hardware.

The bus can also couple the processor to the non-volatile storage. Thenon-volatile storage is often a magnetic floppy or hard disk, amagnetic-optical disk, an optical disk, a read-only memory (ROM), suchas a CD-ROM, EPROM, or EEPROM, a magnetic or optical card, or anotherform of storage for large amounts of data. Some of this data is oftenwritten, by a direct memory access process, into memory during executionof software on the computer system. The non-volatile storage can belocal, remote, or distributed. The non-volatile storage is optionalbecause systems can be created with all applicable data available inmemory.

Software is typically stored in the non-volatile storage. Indeed, forlarge programs, it may not even be possible to store the entire programin the memory. Nevertheless, it should be understood that for softwareto run, if necessary, it is moved to a computer-readable locationappropriate for processing, and for illustrative purposes, that locationis referred to as the memory in this paper. Even when software is movedto the memory for execution, the processor will typically make use ofhardware registers to store values associated with the software, andlocal cache that, ideally, serves to speed up execution. As used herein,a software program is assumed to be stored at an applicable known orconvenient location (from non-volatile storage to hardware registers)when the software program is referred to as “implemented in acomputer-readable storage medium.” A processor is considered to be“configured to execute a program” when at least one value associatedwith the program is stored in a register readable by the processor.

In one example of operation, a computer system can be controlled byoperating system software, which is a software program that includes afile management system, such as a disk operating system. One example ofoperating system software with associated file management systemsoftware is the family of operating systems known as Windows® fromMicrosoft Corporation of Redmond, Wash., and their associated filemanagement systems. Another example of operating system software withits associated file management system software is the Linux operatingsystem and its associated file management system. The file managementsystem is typically stored in the non-volatile storage and causes theprocessor to execute the various acts required by the operating systemto input and output data and to store data in the memory, includingstoring files on the non-volatile storage.

The bus can also couple the processor to the interface. The interfacecan include one or more input and/or output (I/O) devices. The I/Odevices can include, by way of example but not limitation, a keyboard, amouse or other pointing device, disk drives, printers, a scanner, andother I/O devices, including a display device. The display device caninclude, by way of example but not limitation, a cathode ray tube (CRT),liquid crystal display (LCD), or some other applicable known orconvenient display device. The interface can include one or more of amodem or network interface. It will be appreciated that a modem ornetwork interface can be considered to be part of the computer system.The interface can include an analog modem, isdn modem, cable modem,token ring interface, satellite transmission interface (e.g. “directPC”), or other interfaces for coupling a computer system to othercomputer systems. Interfaces enable computer systems and other devicesto be coupled together in a network.

In the example of FIG. 1, the stations 106 are coupled to the wirelessnetwork 102. In a specific implementation, the stations 106 includewireless devices or clients that are coupled to the wireless network102. The stations 106 can be referred to as being “on” or “in” thewireless network 102. Depending upon the context, it may be useful todistinguish between the stations 106, such as by dividing the stations106 into those that are attempting to establish a link with the fastantenna pattern group matching station 104, those that have alreadyestablished a link through the fast antenna pattern group matchingstation 104, those that have already established a link through someother station (not shown), or in some other applicable manner.

In the example of FIG. 1, the network 108 is coupled to the fast antennapattern group matching station 104. In various implementations, thenetwork 108 can include practically any applicable type ofcommunications network, such as the Internet or infrastructure network.The term “Internet” as used in this paper refers to a network ofnetworks that use certain protocols, such as the TCP/IP protocol, andpossibly other protocols, such as the hypertext transfer protocol (HTTP)for hypertext markup language (HTML) documents that make up the WorldWide Web (“the web”). More generally, the network 108 can include, forexample, a wide area network (WAN), metropolitan area network (MAN),campus area network (CAN), or local area network (LAN), but the network108 could at least theoretically be of any size or characterized in someother fashion (e.g., personal area network (PAN) or home area network(HAN), to name a couple of alternatives). In a specific implementationin which the fast antenna pattern group matching station 104 isimplemented as a WAP, the network 108 includes an infrastructurenetwork. In a specific implementation in which the fast antenna patterngroup matching station 104 is part of an ad hoc network, the network 108is less likely to include an infrastructure network.

Networks can include enterprise private networks and virtual privatenetworks (collectively, private networks). As the name suggests, privatenetworks are under the control of a single entity. Private networks caninclude a head office and optional regional offices (collectively,offices). Many offices enable remote users to connect to the privatenetwork offices via some other network, such as the Internet. Theexample of FIG. 1 is intended to illustrate a network 108 that may ormay not include more than one private network. In specificimplementations, the network 108 can be implemented as a WAN, publicswitched telephone network (PSTN), cellular network, or some othernetwork or combination of similar or different networks capable ofcoupling two private networks.

FIG. 2 depicts a diagram 200 of an example of a system for antennapattern group matching. In the example of FIG. 2, the diagram 200includes a computer-readable medium 202, a dynamic antenna device 204,stations 206-1 to 206-N (stations 206), a wireless network access engine208, a stations datastore 210, an antenna pattern group assignmentengine 212, a station antenna pattern profiles datastore 214, an antennapattern group search engine 216, an antenna pattern groups datastore218, and an antenna pattern grouping engine 220.

In the example of FIG. 2, the computer-readable medium 202 is intendedto represent a variety of potentially applicable technologies. Where twocomponents are co-located on a device, the computer-readable medium 202can include a bus or other data conduit or plane. Where a firstcomponent is co-located with the dynamic antenna device 204 and a secondcomponent is located on a different device, the computer-readable medium202 can include a wireless or wired back-end network or LAN. Thecomputer-readable medium 202 can also encompass a relevant portion of aWAN or other network, if applicable.

In the example of FIG. 2, the dynamic antenna device 204 is coupled tothe computer-readable medium 202. In a specific implementation, thedynamic antenna device 204 is configured to turn electrical signals intoelectromagnetic (e.g., radio) waves, and vice versa. In specificimplementations, the dynamic antenna device 204 includes a rigidmetallic structure that is sometimes referred to as an “antenna,” a wireform structure that is sometimes referred to as an “aerial,” or someother applicable structure. In this paper, “aerials,” “antennas,” andother structures with applicable functionality are referred to asantennas. The dynamic antenna device 204 may or may not include (orcould be characterized as including) a support structure, enclosure, orthe like. The dynamic antenna device 204 may or may not includeadditional components such as, for example, an integrated preamplifieror mixer, reflective or directive elements or surfaces (e.g., parasiticelements, parabolic reflectors or horns that serve to directelectromagnetic beams or other desired radiation pattern, etc.), or thelike.

In a specific implementation, the dynamic antenna device 204 includes anarrangement of metallic conductors (“elements”), electrically connectedto a receiver or transmitter. An oscillating current of electrons forcedthrough the dynamic antenna device 204 by a transmitter will create anoscillating magnetic field around the elements, while the charge of theelectrons also creates an oscillating electric field along the elements.These time-varying fields, when created in the proper proportions,radiate away from the antenna into space as a moving transverseelectromagnetic field wave. Conversely, during reception, theoscillating electric and magnetic fields of an incoming radio wave exertforce on the electrons in the elements, causing them to move back andforth, creating oscillating currents in the dynamic antenna device 204.In a specific implementation, the dynamic antenna device 204 includes adirectional or high gain antenna. In another specific implementation,the dynamic antenna device 204 includes an omnidirectional antenna.

The dynamic antenna device 204 can include separate antenna arrays fortransmission and reception of radio signals, or can include an antennaarray that is used for both transmission and reception of radio signals.As used in this paper, an antenna array is intended to include one ormore antennas. (An antenna array with one and only one antenna canalternatively be referred to as “an antenna array,” “an antenna,” or “anantenna array with one antenna.”) In transmission, a radio transmittersupplies an oscillating radio frequency electric current to terminals ofthe dynamic antenna device 204, and the dynamic antenna device 204radiates the energy from the current as electromagnetic waves. Inreception, the dynamic antenna device 204 intercepts power of anelectromagnetic wave and produces a voltage at its terminals, which isapplied to a receiver to be amplified.

In a specific implementation, the dynamic antenna device 204 includes anantenna array on radio frequency (RF) chains having associatedpolarizations. The mounting locations of antennas of the antenna arraycan be separated to add spatial diversity and directed to cause peakgains in different directions from one another. By selecting differentcombinations of diversities in polarization, space, and gain, MIMOstream de-correlation can be improved and a received signal strengthindicator (RSSI) can be increased in a downlink direction.

In a specific implementation, a first polarization of an antenna arrayof the dynamic antenna device 204 defines an orientation of an electricfield (E-plane) of a radio wave with respect to the Earth's surface andis determined by the physical structure of the antenna(s) of the antennaarray and by an orientation of the antenna(s). It has not related toantenna directionality terms (e.g., “horizontal”, “vertical”, and“circular” in an antenna directionality context). Thus, a simplestraight wire antenna will have one polarization when mountedvertically, and a different polarization when mounted horizontally.

Polarization is the sum of the E-plane orientations over time projectedonto an imaginary plane perpendicular to the direction of motion of theradio wave. In the most general case, polarization is elliptical,meaning that the polarization of the radio waves varies over time. Twospecial cases are linear polarization (the ellipse collapses into aline) and circular polarization (in which the two axes of the ellipseare equal). In linear polarization the antenna compels the electricfield of the emitted radio wave to a particular orientation. Dependingon the orientation of the antenna mounting, the usual linear cases arehorizontal and vertical polarization. In circular polarization, theantenna continuously varies the electric field of the radio wave throughall possible values of its orientation with regard to the Earth'ssurface. Circular polarizations, like elliptical ones, are classified asright-hand polarized or left-hand polarized using a “thumb in thedirection of the propagation” rule. Optical researchers use the samerule of thumb, but pointing it in the direction of the emitter, not inthe direction of propagation, and so are opposite to radio engineers'use.

The dynamic antenna device 204 can be matched with a similarly polarizedstation. The dynamic antenna device 204 can have a default, preset,sticky (e.g., only changing when explicitly changed), or otherpolarization for an initial wireless coupling. After the initialcoupling, the polarization can be changed by selecting an appropriateantenna array, element, or the like. As used in this paper, the dynamicantenna device 204 is “dynamic” at least in the sense that a firstactive antenna array with a first polarization can be electronicallyswitched to a second active antenna array with a second polarization.The first active antenna array can include an applicable one or moredifferent components or an applicable one or more same components with adifferent configuration as the second active antenna array, dependingupon implementation- and/or configuration-specific factors.

Knowledge of the antenna construction can speed matching an antennapattern of the dynamic antenna device 204 with a station. Polarizationis largely predictable from antenna construction but, especially indirectional antennas, the polarization of side lobes can be quitedifferent from that of the main propagation lobe. For radio antennas,polarization corresponds to the orientation of the radiating element inan antenna. A vertical omnidirectional Wi-Fi antenna will have verticalpolarization. An exception is a class of elongated waveguide antennas inwhich vertically placed antennas are horizontally polarized. Manycommercial antennas are marked as to the polarization of their emittedsignals.

In a specific implementation, the dynamic antenna device 204 is capableof MIMO. FIG. 3 depicts a diagram 300 of an example of a MIMO channelbetween a dynamic antenna device 302 and a station 304. The station canbe a wireless device. In the example of FIG. 3, the dynamic antennadevice 302 has, for illustrative purposes only, four transmit antennasx₁, x₂, x₃, and x₄; and the station 304 has, for illustrative purposesonly, four receive antennas y₁, y₂, y₃, and y₄. The path from theantennas x_(N) to the antennas y_(M) may be referred to collectively asa MIMO channel 306.

The MIMO channel 306 is characterized by a matrix H with M rows and Ncolumns, where N is the number of antennas at the dynamic antenna device302, and M is the number of antennas at the station 304. The matrix Hdescribes the channel gains between all transmit-receive antenna pairsof the two matrix mesh elements, i.e. the matrix element h_(ij) in thei^(th) row and j^(th) column of H is the channel gain between the j^(th)transmit antenna and the i^(th) receive antenna. The transmitted signalis a vector X=[x₁, . . . x_(N)], where x_(j) is the signal transmittedfrom the j^(th) antenna of the dynamic antenna device 302. The receivedsignal is a vector Y=[y₁, . . . y_(M)], where y_(i) is the receivedsignal at the i^(th) antenna of the station 304. The received signal atthe i^(th) receive antenna is corrupted by noise and possiblyinterference n_(i), and the vector N=[n₁, . . . , n_(M)] describes thenoise and interference associated with all receive antennas. Thereceived signal vector Y is characterized by the matrix multiplicationY=HX+N, i.e.

${y_{i} = {{\sum\limits_{j = 1}^{N}\;{h_{ij}x_{j}}} + n_{i}}},$so that y_(i) is the sum of signals associated with all transmit signalsx_(j), i=1, . . . , N multiplied by the channel gain h_(ij) from thej^(th) transmit antenna to the i^(th) receiver antenna, plus theadditive noise n_(i) associated with the i^(th) receiver antenna.

Multiple-input and single-output (MISO), single-input andmultiple-output (SIMO), and single-input single-output (SISO) aredegenerate cases of MIMO. MISO is when the receiver has a singleantenna. SIMO is when the transmitter has a single antenna. SISO is whenneither the transmitter nor the receiver have multiple antennas. Theacronym MIMO could be considered to include the degenerate cases, ifapplicable. The techniques may also be applicable to multi-user MIMO(MU-MIMO), cooperative MIMO (CO-MIMO), MIMO routing, OFDM-MIMO, or otherMIMO technologies.

The multiple antennas between the dynamic antenna device 302 and thestation 304 can be used to increase data rates by creating multipleindependent channels between the devices (e.g., via spatialmultiplexing): the maximum number of such data paths that can be createdis the minimum of N and M. Alternatively, transmitted signals can becombined via transmit diversity or beamforming, and/or the receivedsignals can be combined via receive diversity, which increases linkrobustness. Also, beamsteering can be done to steer an antenna beam in agiven direction, which increases range and/or reduces interference.These techniques are not mutually exclusive, and some antennas can beused for spatial multiplexing, others for diversity, and still othersfor beamsteering or beamforming.

Referring once again to the example of FIG. 2, the stations 206 arecoupled to the dynamic antenna device 204. In a specific implementation,the stations 206 can have variable antenna profiles, such as oneantenna, two antennas, three antennas, . . . . The antenna profiles canalso include polarization knowledge derived from device characteristics,such as type of device (e.g., laptop), model, or the like. The greaterthe ability to distinguish between antenna parameters, the greater thenumber of antenna profiles that can be meaningfully distinguished usingtechniques described later. For example, a laptop might have two antennaarrays with preset polarizations; this knowledge can improve the speedwith which an optimal antenna pattern can be found from a finite numberof antenna patterns. As is used in this paper, an optimal antennapattern can be defined as having an estimated highest gain of any of theother discrete antenna patterns from either or both polarization matchesand summation of signals.

In the example of FIG. 2, the wireless network access engine 208 iscoupled to the computer-readable medium 202. In a specificimplementation, the wireless network access engine 208 is responsiblefor helping to establish a link between the wireless network and thestation 206. Relevant functionality can be distributed (e.g., acrossmultiple WAPs), pushed upstream (e.g., to an authentication server), orhandled in some other applicable manner. In a specific implementation,the wireless network access engine 208 also obtains information usefulfor determining appropriate antenna pattern group assignments for thediscrete antenna patterns of the station 206. Such information caninclude polarization values or spatial stream characteristics for theantenna patterns. The polarization values can include one or morediscrete polarization values that can include a non-null, non-redundantcombination of discrete polarization values.

An engine, as used in this paper, includes a dedicated or sharedprocessor and, typically, firmware or software modules that are executedby the processor. Depending upon implementation-specific or otherconsiderations, an engine can be centralized or its functionalitydistributed. An engine can include special purpose hardware, firmware,or software embodied in a computer-readable medium for execution by theprocessor. Herein, changes from one operational mode to another,transformation of data, and other activities may or may not beaccomplished using engines.

In the example of FIG. 2, the stations datastore 210 is coupled to thewireless network access engine 208. In a specific implementation, thestations datastore 210 includes data about the stations 206. Other data,such as account data, routing tables, etc. are likely to be maintainedeither locally at a WAP or upstream, but are not depicted in the exampleof FIG. 2 to better illustrate the components discussed with referenceto FIG. 2.

A datastore, as used in this paper, can be implemented, for example, assoftware embodied in a physical computer-readable medium on a general-or specific-purpose machine, in firmware, in hardware, in a combinationthereof, or in an applicable known or convenient device or system.Datastores in this paper are intended to include any organization ofdata, including tables, comma-separated values (CSV) files, traditionaldatabases (e.g., SQL), or other applicable known or convenientorganizational formats. Datastore-associated components, such asdatabase interfaces, can be considered “part of” a datastore, part ofsome other system component, or a combination thereof, though thephysical location and other characteristics of datastore-associatedcomponents is not critical for an understanding of the techniquesdescribed in this paper. Herein, state and other data can be saved in adatastore.

Datastores can include data structures. As used in this paper, a datastructure is associated with a particular way of storing and organizingdata in a computer so that it can be used efficiently within a givencontext. Data structures are generally based on the ability of acomputer to fetch and store data at any place in its memory, specifiedby an address, a bit string that can be itself stored in memory andmanipulated by the program. Thus some data structures are based oncomputing the addresses of data items with arithmetic operations; whileother data structures are based on storing addresses of data itemswithin the structure itself. Many data structures use both principles,sometimes combined in non-trivial ways. The implementation of a datastructure usually entails writing a set of procedures that create andmanipulate instances of that structure.

In the example of FIG. 2, the antenna pattern group assignment engine212 is coupled to the computer-readable medium 202, the stationsdatastore 210, and the station antenna pattern profiles datastore 214.In a specific implementation, the antenna pattern group assignmentengine 212 uses data in the stations datastore 210 about the stations206 to categorize the stations 206 into antenna pattern groups. Theassigned antenna pattern groups can be stored in the stations datastore210 in association with relevant data structures of the stations 206.The station antenna pattern profiles datastore 214 can be consideredpart of the stations datastore 210, a characteristic which a dotted linecoupling the stations datastore 210 and the station antenna patternprofiles datastore 214 is intended to represent. As such, in a specificimplementation, the antenna pattern group assignment engine 212 storesassigned antenna pattern groups in the station antenna pattern profilesdatastore 214 in association with relevant data structures of thestations 206.

In the example of FIG. 2, the antenna pattern group search engine 216 iscoupled to the computer readable medium 202, the station antenna patternprofiles datastore 214, and the antenna pattern groups datastore 218. Aswas just discussed, the station antenna pattern profiles datastore 214includes data structures of the stations 206 that include stationantenna pattern profiles. The antenna pattern groups datastore 218includes data structures of antenna pattern groups. The antenna patterngroup search engine 216 matches the station antenna pattern profile of astation 206 to an antenna pattern group for that profile. For any givenprofile, the antenna pattern group search engine 216 will match arelevant to one and only one antenna pattern group. Depending upon theimplementation, it may or may not be possible to match a profile thatlacks certain information to a first antenna pattern group and the sameprofile but without the lacking information to a second antenna patterngroup, but the mapping of a given profile to an antenna pattern group isone-to-one or many-to-one. Depending upon the implementation, it may ormay not be possible to change an antenna pattern group so that mapping afirst profile at one time gives a different result than mapping thefirst profile at another time.

In the example of FIG. 2, the antenna pattern grouping engine 220 iscoupled to the computer-readable medium 202 and the antenna patterngroups datastore 218. The antenna pattern grouping engine 220 caninclude an interface to enable a person or artificial agent to create,edit, or delete antenna pattern groups.

In the example of FIG. 2, in operation, the antenna pattern groupingengine 220 receives antenna pattern group data from a person orartificial agent. The antenna pattern grouping engine 220 saves a datastructure in the antenna pattern groups datastore 218 that includesparameters of antenna pattern groups.

In the example of FIG. 2, in operation, the dynamic antenna device 204receives a wireless message from a station 206-1. The wireless messagemay or may not be in response to a wireless message (e.g., a beacon)previously sent from the dynamic antenna device 204. The wirelessnetwork access engine 208 facilitates establishing a link between the206-1 and a service of the wireless network, which typically but notnecessarily includes at least authenticating the station 206-1. Thewireless network access engine 208 stores a data structure in thestations datastore 210 that includes parameters of the station 206-1,such as, e.g., a MAC address.

In the example of FIG. 2, in operation, the antenna pattern groupassignment engine 212 determines from the relevant data structure in thestations datastore 210 a station antenna pattern profile that isappropriate for the station 206-1, given the known parameters of thestation 206-1. The antenna pattern group assignment engine 212 storesthe station antenna pattern profile in the station antenna patternprofiles datastore 214.

In the example of FIG. 2, in operation, the antenna pattern group searchengine 216 matches a data record in the station antenna pattern profilesdatastore 214 of the station antenna pattern profile of the station206-1 to a data record in the antenna pattern groups datastore 218 of anapplicable antenna pattern group of the plurality of antenna patterngroups represented in the antenna pattern groups datastore 218. Theantenna pattern group search engine 216 then searches through antennapatterns of the applicable antenna pattern group in accordance with asearch algorithm. The search algorithm can include, for example,in-order searching of a specific subplurailty of the antenna patterns ofthe applicable one of the antenna pattern groups, selecting a specialsequence of antenna patterns, following some other algorithm thatresults in searching a proper antenna pattern group or subplurality ofthe antenna pattern group.

In the example of FIG. 2, in operation, the wireless network accessengine 208 controls the dynamic antenna device 204 to utilize theantenna pattern matching the antenna pattern profile of a station.Advantageously, the system facilitates rapid searching of antennapattern groups to match individual ones of the station 206, thenconfigures the dynamic antenna device 204 appropriately for each of thestation 206. The increased search speed enables the system to utilizeresources on activities other than search, the alternative beingmatching an antenna pattern in a non-optimal manner. Due to the (atleast) dual advantages of the system, the system can be characterized ashaving “fast antenna pattern group searching” or “optimal efficientantenna pattern group searching.”

FIG. 4 depicts a flowchart 400 of an example of a method for matching aWAP antenna pattern to a station antenna pattern with an unknownparameter. The station can be a wireless device that is coupled to theWAP. In a specific implementation, the WAP has an adaptive array of oneor more antennas that can be manipulated to switch between patterns,polarities, or the like. For an array of multiple antennas, spatial andpolarization diversity can be exploited. Depending upon theimplementation, pattern diversity and transmit/receive diversity canalso be exploited. The flowchart 400 and other flowcharts described inthis paper can be reordered or reorganized for parallel execution, ifapplicable. The method can be implemented using the example system shownin FIG. 2.

In the example of FIG. 4, the flowchart 400 starts at module 402 withdefining discrete polarization values for a supported number of spatialstreams. The supported number of spatial streams can be limited by thecapabilities of a system (e.g., a number of antennas in an antennaarray), but can generally be selected in light of design parameters fora system. Polarization values can be practically infinite in number, butpolarization generally need not be extremely fine because fine-tunematching of polarization has diminishing returns beyond a certain point,which can be selected based upon acceptable design parameters. A 90°polarization mismatch can result in a fairly large dB loss (e.g., −20 dBor worse). A 45° polarization mismatch can result in moderate dB loss(e.g., approximately −3 dB). What is considered acceptable loss willvary depending on design parameters. Even fractional dB loss might beconsidered unacceptable in some instances.

Consider a specific implementation having a design parameter thatdefines less than 45° polarization mismatch as unacceptable; thediscrete antenna patterns can include polarization values of 120°(maximum), 60° (intermediate), and 0° (minimum). These three discretevalues are, in practice, associated with spatial streams. For a singlespatial stream, any of the three distinct polarization values arepossible. Assuming a given antenna pattern is properly matched, it isnot possible to have a 45° polarization mismatch for this specificimplementation because the difference between the three discrete antennapolarizations of the antenna pattern is at most 60° (the greatestpossible mismatch would be 30° for a spatial stream with polarizationmidway between any two spatial streams of the discrete antenna pattern).

For an alternative specific implementation of the preceding paragraph,there are three discrete polarization values: 90° (vertical or v-pol),45° (inclined), and 0° (horizontal or h-pol). (It may be noted that an“undefined” slope is treated as “maximum” slope in this specificimplementation, and in general is treated as being a slope with a highvalue in this paper.) It is expected the maximum slope will correspondto a vertical polarization because of the tendency to refer to verticalpolarizations in the industry, but the maximum and minimum slopes canestablish another range without deviating from the conceptualization.

In a specific implementation with an antenna pattern with four or morediscrete polarization values, the polarization values can be referred toas having maximum, large, small, and minimum values. For example, themaximum, large, small, and minimum values can correspond to 90°, 45°,0°, and −45°, respectively. Equivalently, the maximum, large, small, andminimum values can correspond to 135°, 90°, 45°, and 0°, respectively.

The polarization values that are implemented correspond to polarizationsof antennas that can be matched. An antenna with a polarization that isnot in the discrete set of polarizations implemented is treated as if ithad a polarization of the closest match. As is understood in theindustry, an antenna array of four antennas can match an antenna arrayof one antenna (MISO or SIMO, depending upon the perspective) ormultiple antennas. For any given discrete set of polarizations for anantenna array permutations of antenna patterns can be generated.

In the example of FIG. 4, the flowchart 400 continues to module 404 withdetermining a power set of a combination of the discrete polarizationvalues for the supported number of spatial streams. Strictly speaking, apower set includes the empty set, but for practical purposes (becausethe number of spatial streams in each set corresponds to an antenna) theempty set need not be considered a part of the power set (because zeroantennas is useless for relevant purposes). A combination of thediscrete polarization values is used in lieu of a permutation because anantenna array with two antennas having the same polarization is nobetter at searching for an antenna pattern match than a single antennawith that polarization. For example, the power set for two discretepolarization values, v-pol and h-pol, is { {v-pol}, {h-pol}, {v-pol,h-pol} }. (Note that the empty set is omitted.)

In the example of FIG. 4, the flowchart 400 continues to module 406 withgrouping the discrete antenna patterns into ordered groups of discreteantenna patterns. Here, “discrete antenna patterns” refer to the antennapatterns of the power set of the combination of the discretepolarization values for the supported number of spatial streams.Reference to “a discrete antenna pattern” makes sense in a context inwhich the comprehensive set of discrete antenna patterns is known.(Outside of the relevant context, a discrete antenna pattern is simplyan antenna pattern.) The groups of discrete antenna patterns are orderedin accordance with an optimal antenna pattern search algorithm such thatthe first discrete antenna pattern is searched first. The seconddiscrete antenna pattern searched is either the next discrete antennapattern in the group of discrete antenna patterns or some other discreteantenna pattern to which the search algorithm branches based uponresults of a first search. Thus, an ordered group can comprise one ormore branches. In a specific implementation, the number of spatialstreams is generally known before attempting an antenna pattern search.However, if a search is initiated for a first number of spatial streams,but it turns out a station for which the search is initiated has asecond number of spatial streams, the algorithm can branch to adifferent group of discrete antenna patterns with the second number ofspatial streams.

One manner of grouping discrete antenna patterns is by the number ofdiscrete polarization values. For example, the power set for twodiscrete polarization values, v-pol and h-pol, mentioned in thepreceding paragraph, can have two groups: { {v=pol}, {h-pol}} and{v-pol, h-pol}. The first group is the group of discrete antennapatterns with one discrete polarization value and the second group isthe group of discrete antenna patterns with both discrete polarizationvalues.

FIG. 5 depicts a diagram 500 of a grouping of four spatial streams. Thediagram 500 illustrates an example that includes all discrete antennapatterns for up to four spatial streams (using four antennas), with samepolarizations reduced to a single spatial stream so that there is nomore than one polarization value for a given antenna pattern. Forillustrative simplicity, one of the polarizations is vertical (avertical arrow in the diagram 500), one is horizontal (a horizontalarrow in the diagram 500), and the other two are intermediate (135° and45° arrows in the diagram 500) or slant ±45° polarizations.

In the example of FIG. 5, the diagram 500 includes four antenna patterngroupings 502, 504, 506, and 508. The antenna pattern grouping 502includes four spatial stream antenna pattern cases that reduce to asingle-stream antenna pattern. The four spatial stream antenna patterncases include a vertical, horizontal, and two intermediatepolarizations. These spatial stream antenna pattern cases would match anantenna pattern of up to four antennas, where the up to four antennashave polarizations closest to the relevant spatial streams. Whenmatching a single spatial stream, attempting matches with the antennapattern grouping 502 would yield a cumulative 25% matching probability,up to 100% match with four attempts.

The antenna pattern grouping 504 includes six spatial stream antennapattern cases that each reduce to a two-stream antenna pattern. The sixspatial stream antenna pattern cases include any two of a vertical,horizontal, and two intermediate polarizations. These spatial streamantenna pattern cases would match an antenna pattern of two to fourantennas, where the two to four antennas have polarizations closest toone or the other of the relevant two spatial streams, with at least oneof the two to four antennas having polarizations closest to each one ofthe relevant two spatial streams. When matching a single spatial stream,attempting matches with the antenna pattern grouping 504 would yield a50% matching probability on one attempt and a 100% probability with twoattempts (assuming a second pattern of the group has no polarizationsthat are the same as the first pattern that was attempted).

The antenna pattern grouping 506 includes four spatial stream antennapattern cases that each reduce to a three-stream antenna pattern. Thefour spatial stream antenna pattern cases include all but one of avertical, horizontal, and two intermediate polarizations. These spatialstream antenna pattern cases would match an antenna pattern of three orfour antennas, where the three or four antennas have polarizationsclosest to one of the relevant three spatial streams, with at least oneof the three or four antennas having polarizations closest to each oneof the relevant three spatial streams.

The antenna pattern grouping 508 includes a spatial stream antennapattern case that includes each of a vertical, horizontal, and twointermediate polarizations. This spatial stream antenna pattern casewould match an antenna pattern of four antennas, where the four antennashave polarizations closest to every one of the relevant four spatialstreams. The four spatial stream pattern of antenna pattern grouping508, if the pattern is selected initially, will have a 100% chance ofmatching one spatial stream optimally with a single attempt because asingle spatial stream must optimally match one of the four discretepolarizations. (It may be noted that a single spatial stream could atleast in theory fall exactly between two polarizations of the antennapattern, in which case either of the two adjacent polarizations could beconsidered an optimal match.)

Other than for single spatial streams, optimally matching an unknownantenna pattern with one try requires some luck. It may be noted,however, that optimally matching two spatial streams (eventually) can beaccomplished by attempting matches within antenna pattern grouping 504and optimally matching three spatial streams (eventually) can beaccomplished by attempting matches within antenna pattern grouping 506.

In a specific implementation with an antenna pattern with five or morediscrete antenna polarizations a station can have, the polarizationvalues can be referred to as having maximum, large, intermediate, small,and minimum slopes. In a specific implementation, the discrete antennapolarization values can include maximum, minimum, and ‘n’ intermediateslopes, where ‘n’ is a non-negative integer. As ‘n’ approaches ∞, themaximum value approaches 180°, where the minimum value is defined as 0°(horizontal).

Adjacent ones of the discrete antenna polarizations may or may not beseparated by the same amount. For example, the difference between amaximum polarization angle and an intermediate polarization angle andthe difference between an (“the” if the example is of a pattern withthree spatial streams) intermediate polarization angle and a minimumpolarization angle are the same.

Referring once again to the example of FIG. 4, the flowchart 400continues to module 408 with receiving an antenna pattern predispositionindicator from a station. In a specific implementation, the antennapattern predisposition indicator is data sufficient to identify acharacteristic of an antenna pattern. For example, a station can send aMAC address that is known to (or from which information can be derivedby) a receiving device, such as a WAP, either at the device or throughthe device using an off-device agent, such as an authentication server,controller, or other apparatus. As another example, the station couldprovide a proprietary or standards-compliant antenna patternpredisposition indicator to enable the station to be identified as alaptop device, a mobile phone, or some other device; by brand; or bycapability (e.g., 1×1, 2×2, 3×3, 4×4, . . . MIMO-capable).Alternatively, a receiving station could initially beacon (e.g.,broadcast) a predilection for serving a particular profile of stations,which would presumably result in a larger number of stations with thatparticular profile attempting to authenticate through the receivingstation. In this alternative, an authentication request (or othermessage) from a station can itself be treated as an antenna patternpredisposition indicator.

In the example of FIG. 4, the flowchart 400 continues to module 410 withprofiling the station. A station can be profiled as part of anauthentication procedure. Information about the station is typicallystored at a WAP with which the station attempts to authenticate and mayor may not be stored further upstream, as well. In a specificimplementation, profiling a station involves determining a profile intowhich a station fits with a highest probability, which may or may notsimply be a default profile when the antenna pattern predispositionindicator provides relatively little applicable information. The profilecan be characterized as a “preliminary” profile prior to attempting tosearch for an optimal antenna pattern for the station.

A station that has authenticated previously or is associated with a useraccount may have associated data that facilitates production of anaccurate profile of the station. A profile that has been applied to astation before can be characterized as a “historical” profile because itwas presumably a good profile before. Historical profiles can helpdetermine an optimal antenna pattern by, for example, identifying adifference between polarities of two antennas on a station with atwo-antenna antenna array. Specifically, if a station previously matchedan optimal antenna pattern that had two associated spatial streams withpolarities 90° different from one another, an antenna pattern with twospatial streams with polarities 90° different from one another is a goodfirst antenna pattern candidate. It may be the case that the antennasare now oriented differently (as is frequently the case for mobiledevices as they are moved), but that the historical profile is knownwill typically facilitate a faster optimal antenna pattern match byoffering an intelligent starting point and identifying a relevant numberof spatial streams (two in this example) that are likely to be employed.

The WAP can determine a characteristic of an antenna pattern of thestation by looking up a MAC address of the station. Alternatively, theWAP could determine some other characteristic about a device and deducean antenna pattern characteristic. For example, if a station provides anantenna pattern predisposition indicator that enables the station to beidentified as a laptop device, the WAP may assume a certain antennapattern characteristic to speed a search for an optimal match (e.g., twospatial streams, one h-pol and one v-pol, if that is the most commonlaptop configuration). A station could identify itself as a mobilephone, in which case the WAP may know that a single spatial stream ismost likely. A station could identify itself as a specific brand of adevice, with a known antenna pattern characteristic. Stations thatprovide data sufficient to enable the WAP to profile the station withimproved probability over a baseline (e.g., an arbitrary guess) can havea profile that is characterized as an “instructive” profile.

In some cases, the WAP might not have sufficient data to successfullydeduce an antenna pattern characteristic from the antenna patternpredisposition indicator, and can instead match the station to a “commondenominator” antenna pattern that is selected for the purpose ofproviding the best starting point in an optimal antenna pattern search.In a specific implementation, the common denominator antenna pattern isalways the starting point in an optimal antenna pattern search, and theantenna pattern predisposition is incorporated later or not at all.

In the example of FIG. 4, the flowchart 400 continues to module 412 withinitiating an antenna pattern search for a group of discrete antennapatterns associated with the profile for the station. In a specificimplementation, the common denominator antenna pattern is one thatincludes each of the discrete polarizations that can make up a discreteantenna pattern. For example, referring briefly to the example of FIG.5, the antenna pattern grouping 508 illustrates a set of a singleelement having an antenna pattern with each of the discretepolarizations that can make up a discrete antenna pattern, given theparameters of the example. An advantage of the common denominatorantenna pattern is that it optimally matches a single spatial stream(e.g., a pattern similar to group 502 of FIG. 5) 100% of the time. Ahistorical profile (or instructive profile) will not necessarily resultin an improved search for a station with a one-antenna antenna arraybecause changing the orientation of the device can change thepolarization of the antenna. Accordingly, a common denominator antennapattern can be selected in lieu of attempting to match the historicalprofile.

A two-antenna antenna array can have an antenna pattern that does notnecessarily optimally match in one attempt. Consider a station with av-pol antenna and an h-pol antenna. The common denominator antennapattern optimally matches the v-pol antenna and the h-pol antenna,resulting in an optimal match with a single attempt. An advantage of thecommon denominator antenna pattern is that it optimally matches twospatial streams 50% of the time (e.g., when the spatial streams have apattern similar to group 504 of FIG. 5).

In the example of FIG. 4, the flowchart 400 continues to decision point414 with determining whether there was an optimal antenna pattern match.If it is determined that there was an optimal antenna pattern match(414-Y), such as after a common denominator match to a single spatialstream antenna pattern, then the flowchart 400 continues to module 416with communicating with the station using the optimal antenna pattern.If, on the other hand, it is determined that there was not an optimalantenna pattern match (414-N), then the flowchart 400 continues tomodule 418 with considering a next discrete antenna pattern for theprofile 418.

It may or may not be advantageous to use the common denominator antennapattern for a profile that can result in failure to find an optimalantenna pattern after a first attempt. An advantage of the commondenominator antenna pattern is that it optimally matches two spatialstreams 100% of the time with two attempts. (As was previouslymentioned, the common denominator antenna pattern can also optimallymatch two spatial streams 50% of the time with one attempt.) Consider astation that takes advantage of spatial diversity, but not ofpolarization diversity (e.g., an antenna array can have two v-polantennas). The common denominator antenna pattern matches one of thespatially diverse antennas (and the other spatial streams are notoptimally matched). If it is known from the station's profile that thestation has two antennas, or this can otherwise be determined usingspatial diversity or other techniques, and one antenna is matched usingthe common denominator antenna pattern, by changing one of thenon-matching antennas at, e.g., a WAP to have the same polarizationresults in an optimal antenna pattern match. Thus, a station with atwo-antenna antenna array can be optimally matched on a first attempthalf the time (for polarity-diverse antennas) and on a second attempthalf the time (for same-polarity antennas). In theory, the flowchart 400can loop through decision point 414 and module 418 until an optimalmatch is found. However, it may be noted that the purpose of profilingthe station is intended to reduce the number of attempts.

A historical profile can improve the search for a station with atwo-antenna antenna array. If the antennas have different polarizations,the common denominator will optimally match 100% of the time on a firstattempt. However, if the antennas have the same polarizations, thecommon denominator will not optimally match on the first attempt.Accordingly, if a historical profile (or instructive profile) is known,the algorithm can use a different initial antenna pattern. For example,an antenna pattern with two v-pol, an h-pol, and an intermediatepolarization can be attempted for a first match. Because the historicalprofile (or instructive profile) has indicated that the two antennas ofthe antenna array have the same polarization, the initial antennapattern can optimally match with a single attempt 25% of the time. Ifthe h-pol or intermediate polarizations match, a single antenna of theWAP can be adjusted to match the antenna pattern. If calculationssuggest that a negative intermediate polarization (represented as a 135°angle arrow in the example of FIG. 5) is appropriate, two antennas canbe changed to that polarization for an optimal match. It may bedesirable to use the common denominator in lieu of the antenna patternwith two v-pol (or other polarization) values because it may or may notbe difficult to determine whether a polarization that is not representedin the initial pattern (e.g., the 135° angle arrow in the example ofFIG. 5) is the optimal match. The advantage of using the historical (orinstructive) profile results in an improvement of 50% (optimal matchwith first attempt) and 50% (optimal match with second attempt) to 62.5%(optimal match with first attempt) and 37.5% (optimal match with secondattempt). The odds can be further improved if a best guess forpolarizations (e.g., when the polarizations of the station are the same)gives better than 25% chance of hitting, assuming an implementation withfour discrete spatial streams.

Advantageously, for multiple spatial streams up to and including thesupported number of discrete polarization values, starting with thecommon denominator will result in a 100% optimal match with a singleattempt for multiple polarity-diverse antennas. For spatial streams upto and including the supported number of discrete polarization values,starting with the common denominator will result in a 100% optimal matchwith two attempts (one attempt for a single spatial stream) for multiplesame-polarity antennas, assuming it is determined the antennas have thesame polarization.

In a specific implementation, the antenna pattern search is conducted ina manner that depends upon knowledge about the MIMO capabilities of astation. When a station has been profiled to provide such knowledge, thesearch algorithm can be modified to search groups that depend upon theMIMO capabilities. Assume three discrete spatial streams (say, vertical,slanted, and horizontal), grouped into three antenna pattern groups: A(all-same spatial streams, e.g., {vertical, vertical, vertical}), B (twosame spatial streams, e.g., {vertical, vertical, horizontal}), and C(all different spatial streams, e.g., {vertical, slanted, horizontal}).

In order to quickly match a station to an optimal antenna pattern,defined as having maximum gain from either one or both polarizationmatch and a summation of signals from antennas (becausey=h1*x1+h2*x2+h3*x3), the search algorithm is set to consider set Afirst (then C, as a baseline and last resort) if the station is known tohave 1×1 MIMO capabilities. As should be clear from the parameters ofthis example, searching group A takes at most three attempts (e.g.,search {vertical, vertical, vertical}, {slanted, slanted, slanted}, and{horizontal, horizontal, horizontal} in any order), with a fourth searchfor what could be characterized as an error or inability to find amatch.

In order to quickly match a station to an optimal antenna patterndefined as having maximum gain from either one or both polarizationmatch and a summation of signals from, the search algorithm is set toconsider set A first, then set B (and finally C, as a baseline and lastresort) if the station is known to have 2×2 MIMO capabilities. Set A canbe searched first because it is the smallest group that offers themaximum gain if it matches (3 patterns in this example). It should beclear from the parameters of this example, searching group A can fail toresult in an optimal match for a 2×2 MIMO station with two antennashaving different polarizations. Accordingly, in cases in which twoantennas of the station have different polarizations, a search usinggroup B commences, which should result in an optimal pattern match fordifferent-polarity antennas of a station. Within the parameters of thisexample, group B can be defined as three combinations, which is,advantageously, significantly smaller in number than a permutation.Thus, in a worst case, within the parameters of this example, a 2×2 MIMOstation can be optimally matched in at most three attempts forsame-polarity antennas and at most six attempts for different-polarityantennas. As with 1×1 MIMO antenna pattern searching, a final searchusing set C can be characterized as an error or inability to find amatch.

Alternatively, if the polarization of a station's antennas is known orcan be predicted at greater than even odds initially, the searchdescribed in the preceding paragraph can be improved. If polarization isthe same for the two antennas, an optimal search order is set A, thenset B (and then, optionally, set C), as described previously. Ifpolarization is different for the two antennas, an optimal search orderis set B, then set C, and then set A; set B has the highest probabilityof optimally matching, and set C has the second greatest gain with thesmallest set of patterns within the parameters of this example. Aninformative profile (e.g., whether the station is a laptop, and theprobability that a laptop will have same-polarity or different-polarityantennas if capable of 2×2 MIMO) can make this alternative even morepowerful.

In order to quickly match a station to an optimal antenna pattern,defined as having a maximum gain from either or both polarization matchand a summation of signals from, the search algorithm is set to considerset A first, then set B (and finally C, as a baseline and last resort)if the station is known to have 3×3 MIMO capabilities. If it can beassumed two of the three antennas will have the same polarization, as isthe case for most laptops, the search order should be set B first andthe second search order will depend upon the number of discretepolarizations, n. If n=3, set C will have only one pattern and should besearched next. If n=4, set C will have the same number of patterns asset A, but A may be the more probably pattern to match; so set A shouldbe searched next (if set C is a highly probably candidate, set C couldbe searched next instead, even if n=4).

Currently, 4×4 MIMO solutions often use the fourth spatial stream toimprove reliability and range. Groupings of antenna patterns, such asillustrated in the example of FIG. 5, can be used in a manner similar tothe example just described, but for 4×4 MIMO as long as the spatialstreams are matched to spatial streams of stations. It is less likelyfor a station to have a 4×4 MIMO antenna array, but as long as theincreased cost associated with 4×4 MIMO does not interfere withadoption, stations are not unlikely to implement it. Unfortunately,battery resources are consumed more rapidly with 4×4 MIMO, making itunlikely that smart phones will have 4×4 MIMO capability in the nearfuture, at least on any widely adopted scale. (That is, there may be nodifficult technological barriers, but there may be practical ones.) Withthe practical limitations in mind, it may be desirable for a WAP to use4×4 MIMO with stations that match an instructive profile of a smallernumber of expected spatial streams by using group 508 (see FIG. 5)initially, which has previously been referred to in this paper as thecommon denominator. It is reasonably likely 5×5 MIMO will become readilyavailable before long. When it does, starting with the commondenominator may become even more advantageous.

FIG. 6 depicts a flowchart 600 of an example of a method for antennapattern matching at a WAP. The example of FIG. 6 can be implementedusing the example system shown in FIG. 2. In the example of FIG. 6, theflowchart 600 starts at module 602 with grouping discrete antennapatterns into station antenna pattern profiles. Discrete antennapatterns are all combinations of discrete spatial streams that can makeup an antenna pattern recognized by the WAP. The WAP groups combinationsof antennas that form different antenna patterns, into station antennapattern profiles that can each associate with or define a particularstation type. Station antenna pattern profiles can define a particularstation type by degree of MIMO capability (e.g., 1×1, 2×2, etc.) andpotentially by other capabilities or characteristics, such as spatialstream characteristics. The spatial stream characteristics can includethe frequency bandwidths of the spatial streams. Station antenna patternprofiles can also define a station by one or more discrete antennapolarization values for the station.

In the example of FIG. 6, the flowchart 600 continues to module 604 withdetermining a station is of a station type. Station types can bedetermined from a historical profile or account, or they can be profiled“on the fly” as a station communicates with the WAP. A station can beprofiled by using data provided by the station (e.g., by receiving astation type identifier or an antenna pattern predisposition indicatorfrom the station) or derived from the communication with the station(e.g., by deriving station type from an indirect antenna patternpredisposition indicator).

In the example of FIG. 6, the flowchart 600 continues to module 606 withselecting an antenna pattern group corresponding to the station type.The selection is to provide a fast, optimal antenna pattern match.

In the example of FIG. 6, the flowchart 600 continues to module 608 withconducting an antenna pattern search for the station using the antennapattern group corresponding to the station type. The WAP may or may notfollow a special sequence of antenna patterns in the antenna patterngroup corresponding to the station type to do the search.

Convergence time can be shortened when using an RSSI-assisted antennapattern search algorithm. Because RSSI is known prior to sending a firsttraining packet, and because of the strong correlation between the RSSIand data rate, an initial data rate can be selected based on RSSI. Usingdefault antennas for initial training can help to narrow the searchrange. This technique can be implemented using a lookup table listingRSSI and data rate.

FIG. 7 depicts a diagram 700 of an example of a wireless network systemwith a smart antenna wireless network device. In the example of FIG. 7,the diagram 700 includes a wireless network 702, stations 704-1 to 704-N(collectively referred to as “the stations 704”) coupled to the wirelessnetwork 702, and a wireless network device 706 coupled to the wirelessnetwork 702.

In the example of FIG. 7, the wireless network 702 is intended torepresent a wide variety of applicable wireless network technologies. Asused herein, a wireless network refers to any type of wireless network,including but not limited to a structured network or an ad hoc network.Data on a wireless network is often encrypted. However, data may also besent in the clear, if desired. With encrypted data, a rogue device willhave a difficult time learning any information (such as passwords, etc.)from clients before countermeasures are taken to deal with the rogue,assuming countermeasures are necessary.

The wireless network 702 may or may not be IEEE 802.11-compatible. Inthis paper, 802.11 standards terminology is used by way of relativelywell-understood example to discuss implementations that include wirelesstechniques. For example, a station, as used in this paper, may bereferred to as a device with a media access control (MAC) address and aphysical layer (PHY) interface to a wireless medium that complies withthe IEEE 802.11 standard. Thus, for example, stations and a wirelessaccess point (WAP) with which the stations associate can be referred toas stations, if applicable. IEEE 802.11a-1999, IEEE 802.11b-1999, IEEE802.11g-2003, IEEE 802.11-2007, and IEEE 802.11n TGn Draft 8.0 (2009)are incorporated by reference. As used in this paper, a system that is802.11 standards-compatible or 802.11 standards-compliant complies withat least some of one or more of the incorporated documents' requirementsand/or recommendations, or requirements and/or recommendations fromearlier drafts of the documents, and includes Wi-Fi systems. Wi-Fi is anon-technical description that is generally correlated with the IEEE802.11 standards, as well as Wi-Fi Protected Access (WPA) and WPA2security standards, and the Extensible Authentication Protocol (EAP)standard. In alternative embodiments, a station may comply with adifferent standard than Wi-Fi or IEEE 802.11, may be referred to assomething other than a “station,” and may have different interfaces to awireless or other medium.

IEEE 802.3 is a working group and a collection of IEEE standardsproduced by the working group defining the physical layer and data linklayer's MAC of wired Ethernet. This is generally a local area networktechnology with some wide area network applications. Physicalconnections are typically made between nodes and/or infrastructuredevices (hubs, switches, routers) by various types of copper or fibercable. IEEE 802.3 is a technology that supports the IEEE 802.1 networkarchitecture. As is well-known in the relevant art, IEEE 802.11 is aworking group and collection of standards for implementing wirelesslocal area network (WLAN) computer communication in the 2.4, 3.6 and 5GHz frequency bands. The base version of the standard IEEE 802.11-2007has had subsequent amendments. These standards provide the basis forwireless network products using the Wi-Fi brand. IEEE 802.1 and 802.3are incorporated by reference.

In a specific implementation, the wireless network 702 includes a WLAN.Administrative control of a WLAN may or may not include ownership ofhardware for an implementation that includes offering computingresources as a service. In a specific implementation, the wirelessnetwork 702 includes or is coupled to a cloud network.

In the example of FIG. 7, the stations 704 can be implemented asstations in an infrastructure network or an ad hoc network. The stations704 can be referred to as being “on” or “in” the wireless network 702.Stations can include a computer system with a wireless network accessinterface.

A computer system, as used in this paper, is intended to be construedbroadly. In general, a computer system will include a processor, memory,non-volatile storage, and an interface. A typical computer system willusually include at least a processor, memory, and a device (e.g., a bus)coupling the memory to the processor. The processor can be, for example,a general-purpose central processing unit (CPU), such as amicroprocessor, or a special-purpose processor, such as amicrocontroller.

The memory can include, by way of example but not limitation, randomaccess memory (RAM), such as dynamic RAM (DRAM) and static RAM (SRAM).The memory can be local, remote, or distributed. As used in this paper,the term “computer-readable storage medium” is intended to include onlyphysical media, such as memory. As used in this paper, acomputer-readable medium is intended to include all mediums that arestatutory (e.g., in the United States, under 35 U.S.C. 701), and tospecifically exclude all mediums that are non-statutory in nature to theextent that the exclusion is necessary for a claim that includes thecomputer-readable medium to be valid. Known statutory computer-readablemediums include hardware (e.g., registers, random access memory (RAM),non-volatile (NV) storage, to name a few), but may or may not be limitedto hardware.

The bus can also couple the processor to the non-volatile storage. Thenon-volatile storage is often a magnetic floppy or hard disk, amagnetic-optical disk, an optical disk, a read-only memory (ROM), suchas a CD-ROM, EPROM, or EEPROM, a magnetic or optical card, or anotherform of storage for large amounts of data. Some of this data is oftenwritten, by a direct memory access process, into memory during executionof software on the computer system. The non-volatile storage can belocal, remote, or distributed. The non-volatile storage is optionalbecause systems can be created with all applicable data available inmemory.

Software is typically stored in the non-volatile storage. Indeed, forlarge programs, it may not even be possible to store the entire programin the memory. Nevertheless, it should be understood that for softwareto run, if necessary, it is moved to a computer-readable locationappropriate for processing, and for illustrative purposes, that locationis referred to as the memory in this paper. Even when software is movedto the memory for execution, the processor will typically make use ofhardware registers to store values associated with the software, andlocal cache that, ideally, serves to speed up execution. As used herein,a software program is assumed to be stored at an applicable known orconvenient location (from non-volatile storage to hardware registers)when the software program is referred to as “implemented in acomputer-readable storage medium.” A processor is considered to be“configured to execute a program” when at least one value associatedwith the program is stored in a register readable by the processor.

In one example of operation, a computer system can be controlled byoperating system software, which is a software program that includes afile management system, such as a disk operating system. One example ofoperating system software with associated file management systemsoftware is the family of operating systems known as Windows® fromMicrosoft Corporation of Redmond, Wash., and their associated filemanagement systems. Another example of operating system software withits associated file management system software is the Linux operatingsystem and its associated file management system. The file managementsystem is typically stored in the non-volatile storage and causes theprocessor to execute the various acts required by the operating systemto input and output data and to store data in the memory, includingstoring files on the non-volatile storage.

The bus can also couple the processor to the interface. The interfacecan include one or more input and/or output (I/O) devices. The I/Odevices can include, by way of example but not limitation, a keyboard, amouse or other pointing device, disk drives, printers, a scanner, andother I/O devices, including a display device. The display device caninclude, by way of example but not limitation, a cathode ray tube (CRT),liquid crystal display (LCD), or some other applicable known orconvenient display device. The interface can include one or more of amodem or network interface. It will be appreciated that a modem ornetwork interface can be considered to be part of the computer system.The interface can include an analog modem, isdn modem, cable modem,token ring interface, satellite transmission interface (e.g. “directPC”), or other interfaces for coupling a computer system to othercomputer systems. Interfaces enable computer systems and other devicesto be coupled together in a network.

In the example of FIG. 7, the wireless network device 706 can beimplemented as a station, such as an access point. In the example ofFIG. 7, the wireless network device 706 includes RF chain hardware 708-1to 708-N (collectively referred to as “the RF chains 708”) and anoptional infrastructure network interface 718. The wireless networkdevice 706 may or may not include additional components such as, forexample, an integrated preamplifier or mixer, reflective or directiveelements or surfaces (e.g., parasitic elements, parabolic reflectors orhorns that serve to direct electromagnetic beams or other desiredradiation pattern, etc.), or the like.

In the example of FIG. 7, the infrastructure network interface 718 canbe coupled to a network having practically any applicable type ofcommunications network, including the Internet. The term “Internet” asused in this paper refers to a network of networks that use certainprotocols, such as the TCP/IP protocol, and possibly other protocols,such as the hypertext transfer protocol (HTTP) for hypertext markuplanguage (HTML) documents that make up the World Wide Web (“the web”).More generally, the network can include, for example, a wide areanetwork (WAN), metropolitan area network (MAN), campus area network(CAN), or local area network (LAN), but the network could at leasttheoretically be of any size or characterized in some other fashion(e.g., personal area network (PAN) or home area network (HAN), to name acouple of alternatives). In a specific implementation in which thewireless network device 706 is part of an ad hoc network, theinfrastructure network interface 718 may be unused, used to couple to anetwork other than an infrastructure network, or omitted.

Networks can include enterprise private networks and virtual privatenetworks (collectively, private networks). As the name suggests, privatenetworks are under the control of a single entity. Private networks caninclude a head office and optional regional offices (collectively,offices). Many offices enable remote users to connect to the privatenetwork offices via some other network, such as the Internet. Theexample of FIG. 7 is intended to illustrate a network that may or maynot include more than one private network. In specific implementations,the network can be implemented as a WAN, public switched telephonenetwork (PSTN), cellular network, or some other network or combinationof similar or different networks capable of coupling two privatenetworks.

Although the RF chains 708 are depicted as distinct, it should beunderstood that certain hardware can be shared by more than one of theRF chains 708. (Some hardware cannot be used simultaneously by multipleRF chains, however.) In a specific implementation, the RF chains 708 areconfigured to turn electrical signals into electromagnetic (e.g., RF)waves, and vice versa.

In the example of FIG. 7, the RF chains 708 include an RF switches 710,“polarization 7” (P1) antennas 712, P2 antennas 714, and Pn antennas716. The “n” of “Pn” is intended to illustrate that the antennas caninclude “n” polarizations, which can vary by implementation. In aspecific implementation, n=4. Consider as an example, P1 can correspondto horizontal polarization, P2 to vertical, P3 to 45 degree, and P4 to−45 degree.

RF switches 710 can be implemented in using applicable convenienttechniques. For example, the RF switch could include an SP4T RF switch.As another example, in a dual band radio context, additional logic, suchas a CPLD could receive input from radio GPIO to control an RF switchfor either a 2 GHz or 5 GHz chain. (A dual band radio chain can betreated as a single RF chain.) The RF switches 710 receive a controlinput that causes the RF switches 710 to switch between antenna inputsand pass RF signal to and from the antennas as specified. Atransmit/receive switch can be considered part of the RF switches 710 oras a separate component that switches in accordance with whether RFchains are in transmit or receive mode.

In specific implementations, the antennas 712-716 include a rigidmetallic structure that is sometimes referred to as an “antenna,” a wireform structure that is sometimes referred to as an “aerial,” or someother applicable structure. In this paper, “aerials,” “antennas,” andother structures with applicable functionality are referred to asantennas. The antennas 712-716 may or may not include (or could becharacterized as including) a support structure, enclosure, or the like.

In a specific implementation, the antennas 712-716 include anarrangement of metallic conductors (“elements”), electrically connectedto a receiver or transmitter. An oscillating current of electrons forcedthrough the antenna by a transmitter will create an oscillating magneticfield around the elements, while the charge of the electrons alsocreates an oscillating electric field along the elements. Thesetime-varying fields, when created in the proper proportions, radiateaway from the antenna into space as a moving transverse electromagneticfield wave. Conversely, during reception, the oscillating electric andmagnetic fields of an incoming radio wave exert force on the electronsin the elements, causing them to move back and forth, creatingoscillating currents in the antennas. In a specific implementation, theantennas 712-716 include a directional or high gain antenna. In anotherspecific implementation, the antennas 712-716 include an omnidirectionalantenna.

The antennas 712-716 can include separate antenna arrays fortransmission and reception of radio signals, or can include an antennaarray that is used for both transmission and reception of radio signals.As used in this paper, an antenna array is intended to include one ormore antennas. (An antenna array with one and only one antenna canalternatively be referred to as “an antenna array,” “an antenna,” or “anantenna array with one antenna.”) In transmission, a radio transmittersupplies an oscillating radio frequency electric current to terminals ofthe antennas 712-716, and the antennas 712-716 radiate the energy fromthe current as electromagnetic waves. In reception, the antennas 712-716intercept power of an electromagnetic wave and produce a voltage at theterminals, which is applied to a receiver to be amplified.

In a specific implementation, antenna arrays on radio frequency (RF)chains 708 have associated polarizations. The mounting locations ofantennas of the antenna array can be separated to add spatial diversityand directed to cause peak gains in different directions from oneanother. By selecting different combinations of diversities inpolarization, space, and gain, MIMO stream de-correlation can beimproved and a received signal strength indicator (RSSI) can beincreased in a downlink direction.

In a specific implementation, a first polarization of an antenna arraydefines an orientation of an electric field (E-plane) of a radio wavewith respect to the Earth's surface and is determined by the physicalstructure of the antenna(s) of the antenna array and by an orientationof the antenna(s). It has not related to antenna directionality terms(e.g., “horizontal”, “vertical”, and “circular” in an antennadirectionality context). Thus, a simple straight wire antenna will haveone polarization when mounted vertically, and a different polarizationwhen mounted horizontally.

Polarization is the sum of the E-plane orientations over time projectedonto an imaginary plane perpendicular to the direction of motion of theradio wave. In the most general case, polarization is elliptical,meaning that the polarization of the radio waves varies over time. Twospecial cases are linear polarization (the ellipse collapses into aline) and circular polarization (in which the two axes of the ellipseare equal). In linear polarization the antenna compels the electricfield of the emitted radio wave to a particular orientation. Dependingon the orientation of the antenna mounting, the usual linear cases arehorizontal and vertical polarization. In circular polarization, theantenna continuously varies the electric field of the radio wave throughall possible values of its orientation with regard to the Earth'ssurface. Circular polarizations, like elliptical ones, are classified asright-hand polarized or left-hand polarized using a “thumb in thedirection of the propagation” rule. Optical researchers use the samerule of thumb, but pointing it in the direction of the emitter, not inthe direction of propagation, and so are opposite to radio engineers'use.

Advantageously, the antennas 712-716 can be organized to maximizespatial diversity. FIG. 8 depicts a diagram 800 of an example of anantenna board with spatially diverse antennas.

The diagram 800 includes an antenna mounting structure 802 with a boardmounting device 804, P1 antennas 806-1 to 806-N (collectively referredto as P1 antennas 806), P2 antennas 808-1 to 808-N (collectivelyreferred to as P2 antennas 808), P3 antennas 810-1 to 810-N(collectively referred to as P3 antennas 810). Three polarizations (P1,P2, and P3) are depicted for illustrative purposes only; there could bea different number of polarizations used.

In the diagram 800, the antennas 806-810 are interleaved and positionedover a circle 812. Antenna arrays are organized into groups of P1, P2,and P3 antennas and distributed among circular sectors 814. Two circularsectors (appearing in the example of FIG. 8 as semicircular circularsectors 814-1 and 814-N, referred to collectively as “circular sectors814”) are depicts for illustrative purposes only; there could be adifferent number of circular sectors used. The circular sectors 814 canbe given different names depending upon the central angles that definethem, such as quadrants (90°), sextants (60°) and octants (45°).

In the example of FIG. 8, the antenna mounting structure 802 has acenter around which the circle 812 is defined on a plane. In a specificimplementation, multiple same-size, non-overlapping, adjacent circularsectors 814 define the area enclosed by the circle. Thus, the circularsectors 814 can, in combination, be characterized as fully covering thearea defined by the circle 812. The circle 812 is not intended to existas a physical hardware component. Rather, the circle 812 is drawn forthe purpose of illustrating how the antennas 806-810 fall withincircular sectors 814 of the circle 812.

In the example of FIG. 8, the antennas 806-810 are mounted on theantenna mounting structure 802 over the circle 812. In a specificimplementation, at least a portion of each of the antennas 806-810intersect the circle 812 for at least one circle that can be drawn inspace. In another specific implementation, each of a plurality of arraysof antennas having different polarizations fall within a single one ofthe circular sectors 814. It may be noted that other antennas could beattached to the antenna mounting structure 802 other than the antennas806-810, but such other antennas are ignored for illustrative ease.

The P1 antennas 806 have a first polarization, such as horizontal,vertical, or some other polarization. In a specific implementation, forat least one circle that can be drawn in space, a first subplurality oflines perpendicular to the plane in which the circle 812 is definedextend through respective ones of the P1 antennas 806 and intersect theplane in each circular sector of the plurality of circular sectors.Similarly, a second subplurality of lines perpendicular to the planeextend through respective ones of the P2 antennas 808 and intersect theplane in each circular sector of the plurality of circular sectors and athird subplurality of lines perpendicular to the plane extend throughrespective ones of the P3 antennas 810 and intersect the plane in eachcircular sector of the plurality of circular sectors. In general, thenumber of subpluralities of lines will be equal to the number ofpolarizations (in this example, the number of polarizations happens tobe three).

The board mounting device 804 can be used to attach the antenna mountingstructure 802 to a board. Antenna placement can be around a board thatis located above (or below) the antenna mounting structure 802. Althoughthe board mounting device 804 is depicted as circles in each corner ofthe antenna mounting structure 802 (suggesting mounting pegs forattaching an antenna board comprising the antenna mounting structure 802onto another board), in an alternative implementation, the antennamounting structure 802 can have a hollow central portion, such as arectangular portion inside the circle 812 that does not intersect any ofthe antennas 806-810, the edges of which are attached to another board,such as a control board, radio board, or main board. The board mountingdevice can, in such an implementation, be characterized as the materialused to connect the antenna mounting structure 802 to the board locatedwithin the circle 812.

FIG. 9 depicts a diagram 900 of an example of a wireless network devicewith antennas mounted around a printed circuit board (PCB) edge in acircular manner. The diagram 900 includes a PCB 902, horizontal-polarity(h-pol) antenna devices 904, vertical-polarity (v-pol) antenna devices906, 45 degree-polarity (45-pol) antenna devices 908, and −45degree-polarity (−45-pol) antenna devices 910. Some effort has been madeto suggest the angles of the antenna devices 904-910 in diagram 900, butthe angles are only for conceptualization of the polarizations of theantennas and should not be treated as actual angles of departure orarrival. The example of FIG. 9 serves to illustrate any of antennasarranged around the PCB 902, whether above, below, or coplanar with(encircling or encompassing) the PCB 902.

Referring once again to the example of FIG. 8, advantageously, theantenna mounting structure 802 can be separated from a main board, radioboard, control board, or the like. This separation enables amanufacturer to create the antenna mounting structure 802 (and/or acorresponding antenna board) from materials that are relativelyinexpensive relative to the semiconductor materials used formanufacturing printed circuit boards. For example, the antenna mountingstructure 802 can be made of fiberglass. In an alternative, the antennamounting structure 802 is located around a co-planar board, such as acontrol board. In this alternative, the antenna mounting structure 802can still be fabricated using less expensive materials, such asfiberglass, than the co-planar board, which may be a PCB.

Referring once again to the example of FIG. 7, the wireless networkdevice 706 can be matched with the stations 704 in accordance withantenna polarization. In a specific implementation, the wireless networkdevice 706 is capable of MIMO.

FIGS. 10A and 10B depict top and side view diagrams 1000A and 1000B ofan example of a wireless network device with an antenna board. Thediagram 1000A is a top view that shows a main board 1002, h-pol antennadevices 1004, v-pol antenna devices 1006, 45-pol antenna devices 1008,−45-pol antenna devices 1010, and an antenna board 1012. The diagram1000B is a side view that shows the main board 1002, h-pol antennadevices 1004, v-pol antenna devices 1006, 45-pol antenna devices 1008,−45-pol antenna devices 1010, and antenna board 1012. The diagram 1000Balso shows a control board 1014, radio boards 1016-1 to 1016-N (referredto collectively as “the radio boards 1016”), and a board mounting device1018.

In a specific implementation, the control board 1014 is separate fromthe antenna board 1012 and the main board 1002 because it is convenient,from a manufacturing standpoint, to form the relevant switchingcircuitry on a separate board. In an alternative implementation, thecontrol board 1014 could be formed between the antennas 1004-1010 on theantenna board 1012. In yet another alternative implementation, thecontrol board 1014 could be formed on the main board 1002.

In a specific implementation, the radio boards 1016 are separate fromthe antenna board 1012 and the main board 1002. For example, the radioboards 1016 can be “plugged into” the main board 1002 as radio hardwaremodules. The number of radio boards 1016 is optional, but in a specificimplementation, the number of radio boards is equal to the number ofbands. For example, a dual-band radio that operates in the 2 GHz and 5GHz ranges could have a first radio board associated with the 2 GHz bandand a second radio board associated with the 5 GHz band. In analternative implementation, the radio boards 1016 can be plugged intothe antenna board 1012 or replaced with radio modules that are formed onthe antenna board 1012. In another alternative implementation, the radioboards 1016 can be replaced with radio modules that are formed on, asopposed to plugged into, the main board 1002.

In a specific implementation, the board mounting device 1018 connectsthe antenna board 1012 to the main board 1002. The control board 1014may be connected to the antenna board 1012 and/or the main board usingsimilar or different board mounting devices.

Changes from one operational mode to another, transformation of data,and other activities may or may not be accomplished using engines. Anengine, as used in this paper, includes a dedicated or shared processorand, typically, firmware or software modules that are executed by theprocessor. Depending upon implementation-specific or otherconsiderations, an engine can be centralized or its functionalitydistributed. An engine can include special purpose hardware, firmware,or software embodied in a computer-readable medium for execution by theprocessor.

These and other examples provided in this paper are intended toillustrate but not necessarily to limit the described embodiments. Asused herein, the term “embodiment” means an embodiment that serves toillustrate by way of example but not limitation. The techniquesdescribed in the preceding text and figures can be mixed and matched ascircumstances demand to produce alternative embodiments.

We claim:
 1. A device comprising: an antenna mounting structure having acenter around which a circle is defined on a first plane; a plurality ofantenna devices mounted on the antenna mounting structure with aclearance from each other in interleaved subpluralities around thecenter of the antenna mounting structure, including: a firstsubplurality of antenna devices having a first polarization and nothaving polarizations orthogonal to the first polarization, including: afirst antenna device with a first point defined thereon, wherein a firstline perpendicular to the first plane intersects the first point and thecircle; a second antenna device with a second point defined thereon,wherein a second line perpendicular to the first plane intersects thesecond point and the circle; wherein the second point is at a distancefrom the first point in a clockwise direction along the circle or aprojection of the circle into a second plane parallel to the firstplane, and a third point defined on a third antenna device is at adistance from the second point in the clockwise direction along thecircle or the projection of the circle into the second plane; a secondsubplurality of antenna devices having a second polarization differentfrom the first polarization and not having polarizations orthogonal tothe second polarization, including: a fourth antenna device with afourth point defined thereon, wherein a third line perpendicular to thefirst plane intersects the fourth point and the circle; a fifth antennadevice with a fifth point defined thereon, wherein a fourth lineperpendicular to the first plane intersects the fifth point and thecircle; wherein the fifth point is a distance from the fourth point in aclockwise direction along the circle or a projection of the circle intothe second plane, and a sixth point defined on a sixth antenna device isa distance from the fifth point in the clockwise direction along thecircle or the projection of the circle into the second plane; a boardmounting device configured to attach the antenna mounting structure to aboard.
 2. The device of claim 1, further comprising: an antenna board,wherein the antenna board includes the antenna mounting structure; amain board, wherein the main board includes the board; a radio boardcoupled to the main board; a control board coupled to the main board andthe antenna mounting structure.
 3. The device of claim 1, wherein theplurality of antenna devices further comprises a third subplurality ofantenna devices having a third polarization different from the firstpolarization and the second polarization and not having polarizationsorthogonal to the third polarization.
 4. The device of claim 1, whereinthe third antenna device and the first antenna device comprise a singleantenna device.
 5. The device of claim 1, wherein the sixth antennadevice and the fourth antenna device comprise a single antenna device.6. A wireless device, comprising: an antenna mounting structure having acenter around which a circle is defined on a plane, wherein a pluralityof same-size, non-overlapping, adjacent circular sectors define an areaenclosed by the circle; a plurality of antenna devices mounted on theantenna mounting structure with a clearance from each other ininterleaved subpluralities around the center of the antenna mountingstructure, including: a first subplurality of antenna devices having afirst polarization and not having polarizations orthogonal to the firstpolarization, wherein a first subplurality of lines perpendicular to theplane extend through respective ones of the first subplurality ofantenna devices and intersect the plane; a second subplurality ofantenna devices having a second polarization different from the firstpolarization and not having polarizations orthogonal to the secondpolarization, wherein a second subplurality of lines perpendicular tothe plane extend through respective ones of the second subplurality ofantenna devices and intersect the plane.
 7. The wireless device of claim6, wherein the antenna mounting structure is made of fiberglass.
 8. Thewireless device of claim 6, further comprising a board mounting deviceconfigured to attach the antenna mounting structure to a printed circuitboard (PCB).
 9. The wireless device of claim 6, further comprising anantenna board, wherein the antenna board comprises the antenna mountingstructure.
 10. The wireless device of claim 6, further comprising a mainboard, wherein the first subplurality of lines and the secondsubplurality of lines do not intersect an area defined as a verticalprojection of the main board onto the plane.
 11. The wireless device ofclaim 10, wherein the plurality of antenna devices are not verticallyaligned with the main board from a top view.
 12. The wireless device ofclaim 10, further comprising an antenna board, wherein the antenna boardcomprises the antenna mounting structure and wherein the main board andthe antenna board are substantially coplanar.
 13. The wireless device ofclaim 10, further comprising a radio module, mounted on the main board,with radio frequency (RF) chain hardware coupled to the plurality ofantenna devices, wherein, the plurality of antenna devices includecomponents that, together with the RF chain hardware, form at least aportion of a plurality of RF chains.
 14. The wireless device of claim 6,further comprising a control board.
 15. The wireless device of claim 6,further comprising a radio board with radio frequency (RF) chainhardware coupled to the plurality of antenna devices, wherein, theplurality of antenna devices include components that, together with theRF chain hardware, form at least a portion of a plurality of RF chains.16. The wireless device of claim 6, wherein the plurality of antennadevices further comprises a third subplurality of antenna devices with athird polarization different from the first polarization and the secondpolarization.
 17. A wireless device, comprising: a means for mountingantenna devices with a clearance from each other in interleavedsubpluralities of different-polarity antennas around a center such thateach of the subpluralities of different-polarity antennas are located atleast in part within one of a plurality of non-overlapping circularsectors of a circle defined around the center; a first subplurality ofantenna devices having a first polarization and not having polarizationsorthogonal to the first polarization, wherein each of the interleavedsubpluralities of different-polarity antennas comprises one of the firstsubplurality of antenna devices; a second subplurality of antennadevices having a second polarization different from the firstpolarization and not having polarizations orthogonal to the secondpolarization, wherein each of the interleaved subpluralities ofdifferent-polarity antennas comprises one of the second subplurality ofantenna devices.
 18. The wireless device of claim 17, furthercomprising: a third subplurality of antenna devices having a thirdpolarization different from the first and second polarizations and nothaving polarizations orthogonal to the third polarization, wherein eachof the interleaved subpluralities of different-polarity antennascomprises one of the third subplurality of antenna devices; a fourthsubplurality of antenna devices having a fourth polarization differentfrom the first, second, and third polarizations, and not havingpolarizations orthogonal to the fourth polarization, wherein each of theinterleaved subpluralities of different-polarity antennas comprises oneof the fourth subplurality of antenna devices.
 19. The device of claim1, wherein the plurality of antenna devices further includes: a thirdsubplurality of antenna devices having a third polarization differentfrom the first and second polarizations and not having polarizationsorthogonal to the third polarization; a fourth subplurality of antennadevices having a fourth polarization different from the first, second,and third polarizations and not having polarizations orthogonal to thefourth polarization.
 20. The wireless device of claim 6, wherein theplurality of antenna devices further includes: a third subplurality ofantenna devices having a third polarization different from the first andsecond polarizations and not having polarizations orthogonal to thethird polarization; a fourth subplurality of antenna devices having afourth polarization different from the first, second, and thirdpolarizations and not having polarizations orthogonal to the fourthpolarization.